1. Field of the Invention
The invention relates to pumps.
2. Background to the Invention
A known form of pump comprises a housing with an inlet for connection to a source of fluid and an outlet for pumped fluid with the inlet and the outlet being spaced apart around a path of a rotor within the housing. The rotor includes at least one surface forming, with the housing, a closed chamber travelling around the housing to convey fluid around the housing.
In such pumps, a problem is the prevention of direct communication between the outlet and inlet. In JP-A-60240890, a flexible film is fixed to a partition wall between the outlet and the inlet and engages partitioning pieces on the rotor. In GB-A-482750, the rotor carries sections that seal against an arcuate surface of the housing. In U.S. Pat. No. 3,282,496 slidable elements are forced by pressure against the chamber-forming surfaces of the rotor. In JP-A-60111078, the rotor carries movable seals formed by various deformable bodies that seal against the housing between the outlet and the inlet. In GB-A-1109374, the rotor carries seals that seal against the housing between the inlet and the outlet